My Bookmarks (Bookmarks menu > Show all bookmarks) is laid out as:
I save my bookmarks in separate folders I create under the "Bookmarks Menu".
When I used to bookmark a page using the option "Bookmarks" menu > "Bookmark this page" I was shown a dialog where I could choose an existing folder for the new bookmark or could create a new folder in which to save it. At some point over the last 6 months or longer (I can't remember for certain) the bookmarks are saved automatically in the "Other Bookmarks" folder and all I see up at the Firefox hamburger icon is a green "Saved to Library" notification.
I cannot find any settings in the "Library" window (Show all bookmarks) or in Firefox "Options" to force that original dialog to show so that I can choose where to save each new bookmark. Any ideas?